The door should be working correctly. To open it, aim at the door, hold down the left mouse button, and drag your mouse in the direction the door opens. For example, if the door opens to the right, drag your mouse to the right.
As for the guide, I think there may have been a misunderstanding. I didn't intend to include it inside the game itself. Instead, I put it in the game's installation folder from the beginning. There's a file called **"A_Tour Information.txt"** that explains the controls and gameplay.
That said, your feedback made me realize that having the guide only in the installation folder isn't obvious enough. I'll consider adding it directly into the game as well.
Thank you for taking the time to play the demo and share your feedback. It really means a lot to me, and your suggestions are very helpful.